Process for the purification of fats and oils



Patented Oct. 4, 1932 UNITED STATES PATENT. OFFICE WILHEIM GENSECKE, F GONZENHEIH, IRANKFORT-ON-THE-MAIN, GmANY,

ASSIGNOR TO AMERICAN LURGI CORPORATION, 01 NEW YORK, N. Y, A CORPORA- TION 01 NEW YORK PROCESS FOR THE PURIFICATION OF FATS AND OILS No Drawing. Application filed April 20, ISSL SeriaI No. 581,609, and in Germany Kay 2, 1980.'

This invention relates to a process for the purification of fats and oils.

vWhen certain kinds of Vegetable or animal fats or oils are neutralized with alkali, and it is desirable that colouring matters and similar impurities should also be eliminated from the oil by the action of the alkali, experience has shown that it is necessary to employ a very considerable excess of the alkali 1 solutions. Moreover since adequate neutralization of the free fatty acids is possibleonl by employing concentrated solutions of-a kali, notable quantities of neutral fat are also saponified by the considerable excess of neu-.

' 'tralizing agents employed in this known,

process. The present invention aims at reducing the losses of neutral oil in neutralizing oils or fats with alkali or the like andyat the 1 same time at improving, as far as possible the elimination of the colouring matters and :imilar impurities from the neutral oils or ats. According to the invention, onl the theoretically necessary amount of a ali, or a slight excess of about 5%, is employed for neutralizing the freefatty acids. The alkali is employed in the form of such a highly concentrated solution that the recipitation of "the fatty acids in the oil or at is practically complete. After drying the fatty-acid soaps in vacuo (which, however, may also be performed during neutralization) and after separating the fatty-acid soaps from the neutral oil or fat, by filtration, centrifuging or,

other suitable means, the colouring matters and other impurities in the neutral oil or fat are removed by alkali solutions in such a dilute condition that the neutral oil is no longer attacked thereby.

It has unexpectedly transpired that an oil or fat which has been neutralized with alkali in order to remove the free fatty acids, can be further treated,forthe extraction of colouring matters and the like, with extremely dilute alkali solution, and that a comparatively small quantity of very dilute alkali solution suflices for such further treatment. The advantage of the herein described process also consists, therefore, in an economy of neutral- 50 izing agents. First-class refined products are obtained which are at least as suitable for further bleaching, if-necessary, and alsofor deodorizing, as those which have been refined with a large excess of alkali, whilst the losses in neutral oil, which are unavoidable in the saponification of fatty' acids with strong lyes, in considerable excess, do not occur, so that,

in this connection also, the new method of treatment represents a valuable technical i111! provement.

It has already been pro osed to, treat oils with very weak, cold lye, or the purpose of removing particles of dirt, soaps, and the like, and then to wash them, first with alkaline water and afterwards with purenwater. It is, however, impossible to obtain a equate saponification of the free fatty aci with weak yes. Moreover, it was the practice, after eliminating the free fatty acids from oils or fatsby distillation, to employ a treatment with weak lyes, for the purpose of removing the free fatty acids remaining after the distillation, and also removing colouring matters and other im urities. The simultaneous elimination 0 fatty acids and impurities from the oil is successful only when a considerable excess of neutralizing agents is employed, andthese must, naturally, be of a concentration suitable for the saponification of the fatty acids, so that the neutral oils are inevitably attacked during the saponification of the fatty acids, I

Example 3000 kg. of crfe' or pre-refined maize oil are placed in an pparatus, in which a vacuum is maintained, and are heated to about 40 (1.,- a quantity of soda lye (for example, of 25 B. strength) corresponding to the amount of free fatty acids resent plus an excess of 5%,being then ad ed, with active stirring. After the free fatty acids have been neutralized, and the fatty-acid soap has been dried, the mixture of oil and soap is filtered, and the filtrate is transferred to an apparatus, fitted with heating appliances and stirrers, in which it is heated to about C. About 8% of dilute caustic soda lye (about 3 B. strength) is then sprinkled over the oil, or added with stirring. Stirring is continued for a short time, after which the oil is left at rest, the dilute lye, which contains the impurities and colouring matters, being afterwards drawn ofi. If necessary, thewashing with lye is repeated. Finally, the oil is washed with hot water, until the last traces of lye have been removed, and the oil is then dried in vacuo.

I claim 1. Process for the purification of animal or vegetable oil or fat material containing besides neutral oil or fat free fatty acid and coloring matter which comprises treating the material with concentrated alkali solution in quantity suflicient to neutralize the free fatty acid content thereof but not more than about 5% in excess of the amount theoretically required and drying in vacuo the fatty acid soap thereby formed, separating the dried fatty acid soap from the mixture, and theres after treating the soap-free mixture with dilute alkali solution whereby to separate coloring matter therefrom.

2. Process as defined in claim 1, in which the dilute alkali solution used in separating coloring matter is of a concentration inefiectual for the saponification of the neutral fat or oil content of the soap-free mixture.

3. Process as defined in claim 1, in which separation of coloring matter is effected by means of an alkali solution of about 3 B. strength.

4. Process as defined in claim 1, in which the treatment with dilute alkali solution is effected by agitating the solution with the soap-free mixture at an elevated temperature, with subsequent settling and separation of the alkali solution containing coloring matter.

In testimony whereof, I afiix my signature.

WILHELM GENSECKE. 

